Control of wool shrinkage by polyamides



Patented July 7, 1953 ,aeamvs CONTROL or wool. SHRINKAGE BY POLYAMIDES Irving Pk-Hammer, Belleville, and John B. Rust, East Hanover',IN. J;, assignorsQ-by direct and inesne' assignments of one-half to Montclair Research Corporation, a corporation of'New Y Jersey and one-half to Ellis-Foster Company, a; corporation of New Jersey y a No Drawing. 1 Application March 17, 1949,

i I Serial No. 82,024 g This invention relates to control of wool'shrinke age by use of polyai'nides and particularlyrelates to shrinkproofed wool of substantiallynormal hand produced by theutilization of water insoluble but organic-solvent-soluble polyamides and polyamide derivativesto' baths for treating wool for these purposes, and to methods ofmaking the baths and of treating the wool. Y

A variety of methods ofshrinkproofing woo have been suggested in the prior -'-art which for the most part havenot proved satisfactory for any one of a number of reasons such' as- (l) shrinkproofing frequently changed the normal hand of the wool making it a product not useful for normal 'purposes i2) degradation-of wool fibers with resulting loss ofw'ear resistance; (3) the treatment was not permanent to resist the normal cleaning and-laundering operations; (4) the material deposited for shrinkproofing'effect was not permanent but underwent either physical or chemical change militatingagainstthe utility of the treated wool; (5) the rnethods'of treating the wool to produce the shrinkproofed product where not commercially feasible; etc.

Among the objects of the present invent1on is the production of shrinkproof woolof substan tially normal handby theutilization of polyamides which although water insoluble, maybe utilized in solution inorganic solve'ntsfor treatof the polyamide in solution.

Still further objects and advantages of the ment of the wool without requiring precipitation present invention will appear from the more detailed description set forth below it being understood that such more detailed description is given by way of illustration and-explanation only, and

not by way of limitation, sinceflvarious changes therein maybe madeby thoseskilled in the art the present invention.

without departing fromj the 'scopeand spirit of In accordance with the present invention,"

shrinkproofed wool is produced :of substantially normal hand by deposition on the wool ofa deposit from an organic solvent solution of 'a' waterinsoluble polyamide in an amount insuificient to modify the normal hand ofthe wool but sufficient to give shrinkproofing, followed by insolubilization of the deposit by heat; In depositing the. wool from such solution, ..;and inwinsolubilizmg such deposit, precipitatingagents arenot em-,

ployed but the. deposition and'iinsolubilization take place Without precipitation of the polyamide:

from the solution without-the utilization of any precipitating agents.

Any water-insoluble polyamide having anio- 36 Claims. (c1. 117-141) carrying out the present invention including the so -ca11ed nylon type filament forming polyamides and such polyamides containing recurring hydrogen-bearing carbonamide groups which have been modified to produce alkylol or alkoxy methyl groups attached to nitrogen in the main polyamide chain. The synthetic linear polyamide employed may be'any of the filament forming polyamides as set forthjand caprolactam, copolymers for epsilon-caprolactani and ethylene 'sebacamide, etc.

Such synthetic linear polyamides utilized for the present'invention, have an intrinsic viscosity of at least 0.4, and contain recurring hydrogen bearing carbonamide groups. Such synthetic linear polyamides, without modification of such hydrogen bearing carbonamide groups, may be employed in an organic solvent solution iii-the treatment of wool to produce shrinkproofed woolof' substantially normal hand. Such synthetic linear polyamides are soluble in acids and phenols, including inorganic acids such as hydrochloric,

nitric, phosphoric, and sulphuric, organic acids such as formic acid, and phenols such as phenol,

cresol, etc; Any such solvents and particularly the organic acids such asfo'rmic acid may desirably be employed as the solvent for the polyamide in'the treatment of the Wool to produce "the shrinkproofed wool of normal hand. For suchv purposes the wool is impregnated with or padded with a solution of the polyamide, todeposit the desired amount of solution on the wool, any excess solution being removed as by squeeze rolls andsubjected to a drying operation at any desired temperature p rticularly below a C. to pro-..

ducea shrinkproofed wool of normal hand. It

:should be notedinthis connection that the wool is treated with the solution of the polyamide and.- no precipitation of the polyamide from the solu tion by means of a precipitating'agent or precip itation by neutralization which is included within precipitating agents just referred to, is employed. The deposition of the material in the solution on the wool takes place during the drying operation without any precipitating agent being employed as just set'forth. A drying operation at r ;a temperature below 100 C. is sufiicient to proparticularly those generally characterized as a polymethylen amide" duce insolubilization directly as the result of such heat treatment. Curing for example by heating the dried deposit at temperatures above 100 C. are not required with such synthetic linear polyamides as have just been described above and the shrinkproofing effect is readily obtained by the use of the drying operation alone, although a curing step may be mployed if desired.

The impregnation or padding of the wool with the bath or solution of polyamide may be carried out in any desired way, mere immersion of the wool in such solution being satisfactory. Such impregnation or padding operation may be carried out at any desired temperature which causes no undesired change in the polyamide derivative at this stage; but the temperature may be relatively low and may for example be desirably carried out at room temperatures or slightly elevated temperatures if desired. The amount of shrinkproofing agent deposited on or in the fibers or the scales thereof should not be sufficient to interfer with the desired hand of the wool. Since small amounts of shrinkproofing agents are all that are needed, the end sought is easily accomplished. The concentration of the polyamide in th solution may be anywhere from 1 to 25% for example and such solutions, the percentages stated being by weight, employed for impregnation or padding of the wool. The amount of deposit of polyamide on the wool need not generally exceed about although it may be as high as but usually will be materially lower and from 2 to 7% by weight with preferable amounts of about 2.5 to 5% by weight will be suflicient for shrinkproofing purposes.

As stated the padded or impregnated wool may be subjected to drying for removal of moisture prior to curing when the latter step is used, or for insolubilizing when curing is not used. Any drying procedure may be employed provided temperatures do not reach those where the polyamide derivative is undesirably affected. Drying will usually be at temperatures below 100 C. therefore with ranges of from 60 to 80 being useful, and if desired vacuum may be employed.

Since synthetic linear polyamides of the type just described above require strong solvents such as acids and phenols for solution, it is generally preferable for commercial purposes to utilize polyamides which have been modified to give them solubility in more conventional organic solvents such as aliphatic alcohols including for example methanol, ethanol, etc. For such purpose therefore the synthetic linear polyamides are desirably converted into N-alkylol polyamides particularly illustrated by the N-methylol derivatives having recurring groups of the formula of producing such N-methylol derivatives are.

given but they are to be considered to be exemplary only of the production. of such N-methylol derivatives. They may be further characterized as the N-methylol derivatives of synthetic linear 4 polyamides having an intrinsic viscosity of more than 0.4 and having recurring hydrogen bearing carbonamide groups in the main polymer chain some of which groups at least are converted into the N-methylol groups. As a general rule at least 10% of such hydrogen bearing carbonamide groups should be converted into N-methylol groups. In the stated examples given below while paraformaldehyde is referred to as utilizable, any formaldehyde yielding material may be employed, the paraform being quite convenient. aqueous formaldehyde may be used. The amount of formaldehyde is desirably from 0.5 to 2.0 parts to 1 part of the polyamide depending on the extent of reaction desired.

While formic acid has been particularly referred to in the examples as the reaction solvent, other organic acids which are solvents for polyamides may be used including the carboxylic acids such as formic, acetic, hydroxy acetic, chloroacetic, etc. Formic acid is conveniently used and may be employed in any concentration such as 70% to 100%, the commercially available formic acid being quite useful. The temperature reaction may be any temperature at which the reactionv takes place for example from about 30 C. above but should. be one below that at which undesired degradation of the polyamide takes place.

The N-methylol polyamides may be utilized in any desired solution for the shrinkproofing of wool. Examples are given below showing the utilization of aqueous formic acid solutions for that purpose, but other types of solutions may be employed. They are soluble in various alkanols and particularly in aqueous alkanols including aqueous ethanol, aqueous methanol, normal propanol, isopropanol, isobutanol, ethylene glycol, etc.

The utilization of the solutions of the N- methylol polyamides for the shrinkproofing of wool may be carried out employing solutions containing percentages of the N-methylol polyamides of from 1 to 25% as set forth above for the synthetic linear polyamides, and the amount of N-methylol polyamide deposited in or on the fibers and the conditions for carrying out the impregnation or padding operation may be the same as those set forth above. Also the wool shrinkproofing effect is readily obtained by drying steps for example at temperatures below C. as set forth above for the synthetic linear polyamides, without any curing operation, but curing operations. at temperatures above 100 C. may be employed in connection with the drying step. Otherwise the manner of producing the shrinkproofed wool with the N-methylol derivatives and is analogous to those set forth above for the synthetic linear polyamides described.

A further form of water-insoluble but organic solvent soluble ynthetic linear .polyamide derivative that may be employed are the N-alkoxy methyl polyamides having recurring groups of the formula or other formaldehyde yielding substances also aeem'ze as explained above in connection with: .=the N -methylol derivatives. Since theyare generally produced from synthetic linear polyamides having an intrinsic viscosity of more than 0.4, and containing hydrogen bearing carbonamide groups recurring in the main polymer chain, with the average number of carbons in the. segments of the chains separating the carbonamide groupsof at least two, these characteristics prevail generally in the N -alkoxy derivatives produced from such synthetic polyamides. The 'alkoxy group present isvusually obtained from. an alcohol .or thioalcohol. Such alcohols include alkanols such as methanol, ethanol, propanol, isopropanol, butanol, octyl alcohol, lauryl alchol, etc., aralkyl alchols in which the alkyl hydrocarbon has the hydroxy group attached to it as in benzyl alcohol, the various glycols such as ethylene glycol, and :glycol ethers such as ethylene glycol methyl ether, diethylene glycol, etc., may all be employed. Mixed alcohols give mixed alkoxy methyl derivatives and can be employed.

The N-alkoxy methyl polyamides may be utilized in various types of solutions for the treatment of the wool to produce shrinkproofing. Common organic solvents which can be employed include particularly the aqueous alkanols such as aqueous methanol, aqueous ethanol, as well asmixtures of alcohols andchlorinated hydrocarbons, for example methanol-chloroform mixtures.

The concentration of modified polyamide'in such solution may vary and may b anywhere from 1 to 25% by weight for example; and such solutions are used for impregnation or padding of the wool in a manner similar to that set forth for other derivatives above producing a deposit in or on the fiber or'scales thereof of an amount of polyamide insufficient tomodify the normal hand of the wool but sufiicient to give the de-- sired shrinkproofing properties. As illustrated above in connection with other materials, from 1 to of such N-alkoxy methylpolyamide may be employed. J a

The deposition of the N-alkoxy methyl polyamide on the wool after impregnation or padding is carried out without utilizing alprecipitating agent and by subjecting the-impregnated" or padded wool directly to a heating operation. Such heating operation desirably includes a drying step by heating the impregnated or padded wool at a temperature below 100 C. preferably at temperatures of from 60 to 80 C. with-or without vacuum to carry out the drying-operation. While in connection withth synthetic linear polyamide such as the. nylons and the N -methylol polyamides as described above,it was pointed out that a drying operation is sufiicient to produce insolubilization of the deposited material and the shrinkproofing effect, with the N-alkoxy methyl polyamides, a curing step is desirably employed in addition to the drying step. Such curing involves a heat treatment at ele-. vated temperatures sufficient to insolubili'ze' the polyamide derivative, and again it should be pointed out that no precipitating agents are employed; Th temperatures used in said curing operation will usually exceed 100 C. and desirably may be in the range of from 120 to 150 C. Since many of the polyamide derivatives can be subjected to much higher temperatures as for example 250 to 285 C. elevated temperatures of this order may be employed but are-usually not desirable with treated woolproducts. 7 However it should be noted that the curing treatmentris.

relatively short for example 15 minutes at C. is. generally sufiicient while shorter treatments sufiice at higher temperatures for example 10 minutes at 13570., afew minutes at C, etc.

Consequently fractions of the stated time. periods may be utilized at the much higher temperatures referred to above, but nevertheless temperatures and times of the order given in examples below are more desirable.

Any of the '-N-alkoxy methyl polyamides referred to immediately above and particularly such derivatives as N-methoxy. methyl hexamethylene adipamide, may be reacted with thiourea to give products which may also be employed in a manner analogous to the N-alkoxy methyl polyamides for the shrinkproofing of wool. The general considerations'given above for the N methoxy methyl polyamides also supply to thethiourea modificatio'nljust'set forth. Ex amples of producing such thiourea'f derivatives are given for illustrative purposes;- The same considerations with'respect to utilization or such thiourea derivatives for shrinkproofing purposes apply as those set forth above connection with the N-alkoxy methyl polyamides."

The following examples are given by way of illustration, parts being by weight unless otherwise indicated.

Example 1 e A solution of 10 parts of a commercialsa-mple of polyhexamethylene adipamide in 90 parts of anhydrous formic acid was prepared at 6070 C. A measured sample of wool wasimmersed in the solution at room'temperature and'the excess solution squeezed out. The weight increase of the wool sample indicated that 25% of the polyamide had been applied. The sample was dried at 60-70 C. and then relaxed'for 2 hours in a 1% soap solution at room temperaturefollowed by a 2 hour laundering at 65 C. with a e pound load and at 0.2% soap solution. .Measurements were taken after each washing-procedure. "An untreated wool sample was relaxed and laundered along with the treate d sample. Thefollowing shrinkage results were obtained. "f

Percent I P0ly- Relaxation Total Laundering Sample amide Shrinkage, Shrinkage, Shrinkage,

' on Percent Pe: cent Percent sample Treated '25 14.5 13.0 3.5

Untreated 0.0 15.2 1s +1945 Example 2 parts of formicacid to yield a 3.3 polyhexa methylene adipamide solution.

Two measured samples of wool were immersed in the 3.3% polyamide solution,andfthe excess solution was then squeezed out. The weight in-t crease of thewool samples indicated that, 3.13% of the polyamide had been applied; The samples were. dried at. (5.0 C, and one of theeemnles-lwea 7 then curedat'l25 C. for hour. Both the cured and uncured sample, along with an untreated sample were then relaxed and laundered in the usual fashion, area measurements being taken after each washing procedure. The following results were obtained.

Percent Poly- Relaxation Total Laundering Sample amide Shrinkage, Shrinkage, Shrinkage,

'on Percent Percent Percent sample Treated, uncured 3. 3 4. 5 4. 5 0.0 Treated, cured.. 3. 3 5. 5 6. 5 1.0 Untreated. 0.0 9. 7 37. 6 27. 9

Ezrample 3 parts of a commercial sample "of polyhexamethylene adipamide were dissolved in '74 parts of 90% formic acid at 60 C. in a 3-neck flask fitted with a stirrer, thermometer and reflux condenser. After dissolution occurred, a solution of 0.012 part of sodium hydroxide and 20 parts of paraformaldehyde .in 26.6 parts of methanol was added with stirring; the temperature during the-addition was maintained at 60 C. The reaction was continued at 60 C. for an additional .30 minutes, during which period 12 parts of methanol was addedtoform a workable solution. The solution was poured into a mixture of 180 parts acetone and 230 parts water with stirring and neutralized by the addition of aqueous ammonium hydroxide. The coagulated product was washed with cold water and then dissolved in 15 0 parts of anhydrous ethyl alcohol. The resulting solution contained 9% solids.

In order to determine the shrinkage-control properties of the material, a 4.5% solution of the polyamide derivative was prepared from 125 parts of the above 9 solution, 100 parts of alcohol and parts of water. The resulting solution was padded onto wool in the usual fashion, and after drying, themeasured wool sample cured at 130 C. for 15 minutes. The following shrinkage data was obtained after relaxation and laundering.

parts of the initial gel obtained in Example 2 was dissolved in 200 parts of 98-100% formic acid. 104'parts of the resulting solution, equivalent to 3.45 parts of the polyhexamethylene adipamide, was dissolved in a-mixture of 99 parts of acetone and 125 parts of water to yield a clear solution. The solution was then neutralized with an aqueous ammonium hydroxide'solution with vigorous stirring. During the neutralization the temperature was kept below 40 Caby means of external cooling. The temperaturewas' then lowered to 10 'C.twith continual stirring and a precipitatesettled out in the form of small round solid balls. The precipitate was filtered off and washed with several portions of cold water until the washings were neutral. 20.7 parts of a water wet .product was obtained which was easily dissolved -at room temperature in parts of anhydrous alcohol to yield a 3.4% solution of the polyamide in 80% alcohol.

Two measured samples of wool were immersed in the alcoholic solution and the excess pad liquor removed. The-samples were dried at 70-80 C. and one of the samples was then cured at 130 C. for 15 minutes. After the'usual relaxation and 20 parts of a commercial sample of polyhexamethylene adipamide was dissolved in 74 parts of formic acid at 60 C. in a reaction flask fitted with a thermometer, stirrer, and air condenser. When solution had occurred, the temperature was maintained at 60 C. and a slurry prepared by adding 20 parts of paraformaldehyde to 33.6 parts of diethylene glycol containing a trace of sodium hydroxide was added with constant stirring. After 10 minutes, the reaction product set up to a pink gel at 60 C. The gel, which contained suspended white particles, was allowed to cool. After 18 hours at room temperature, 200 parts of 90% formic acid was added and the mixture heated to 60 C. with stirring to effect solution of the gel. The resulting solution was poured into 400 parts of solution prepared by mixing equal volumes of acetone and water. A clear solution resulted. The solution was then neutralized with aqueous ammonia. A granular precipitate was formed. After filtration, 75.5 parts of a granular product was obtained which contained theequivalent of 20 parts of the polyhexamethylene adipamide.

18.9 parts of the above product was soluble in 131.1 parts of hot alcohol to yielda 3.3% solution based on the original weight of polyamide.

A sample of wool, measured as described in Example 1 was immersed in the above mentioned 3.3% solution at 50-'60 C. After the excess pad liquid was squeezed out, the weight increase of the wool sample indicated that 3.3% of the polyamide had been applied. The sample was dried at 75 C. and cured at C. for 15 minutes. After the usual Relaxation and laundering process, along with an untreated wool sample, the following shrinkage data'was obtained.

The finished wool sample was not discolored; had a normal, dry hand; and had good draping J characteristics.

scribed in Example 5. The reaction syrup was.

dissolved in an acetone-water solution and neutralized with aqueous ammonia. A fine precipitate resulted which was soluble in hot alcohol. The alcoholic soluble derivative so obtained showed shrinkproofing characteristics when applied to wool. I Example 7 Anhydrous hydrogen chloride was bubbled through a mixture of 3.3 parts of paraformaldee hyde, 7.0 parts of pyridine and 10.0 parts of 98-100% formic acid until a weight increase of I 3.9 parts had been attained. The resulting solution was clear except for some undissolved paraform. The clear portion of this solution was added to a solution of 10 parts of a commercial sample of polyhexamethylene adipamide in parts of 98-100% formic acid at 60 C. The mixture gelled quickly. 30 parts of theresultinggel was dissolved in 116 parts of anhydrous formic acid. The resulting solution was-treated with a mixture of 139 parts of acetone and 175 parts of water to form a clearsolution and the polyamide derivative was precipitated with aqueous ammonium hydroxide in the manner described in Examplei. I

15.5 parts of a'water-wet product was obtained which was soluble in 1345 parts of anhydrous alcohol to yield a 3.1% solution based on the weight of the polyamide.

The shrinkproofing properties of the derivative was determined in the usual fashion and the following results were obtained. Thetreated' wool sample was cured at 130 C. for 15 minutes.

Percent Poly- Relaxation Total Laundering Sample amide Shrinkage, Shrinkage, Shrinkage,

on Percent Percent Percent sample Treated 3.1 3.5 10.4 6.9 Untreated 0.0 11.7 4 48.8 37.5

li'zramplev 8 60 parts of paraformaldehyde was dissolved in 60 parts of methyl alcohol containing a trace of sodium hydroxide by heating to 60. C'. This solution, while at 60 C., was addedto a solution of 60 parts of a commercial sample .of a polyhexamethylene adipamide in 180 partsoff90%'j formic acid at 60 C. and contained in a reaction flask fitted with a thermometer, stirrer, and condenser. The paraform solution was added slowly during the first minute and then more rapidly so that the addition was complete in 3 minutes.

10 minutes after the formaldehyde addition the 7 mixture gelled. parts of methanol was added, rapidly and with gradual stirring, dissolution of the geloccurred and the reaction was continued 1 at 60 C. for an additional 15 minutes. There action mass was poured into a mixture of 673 parts of acetone and 850 parts of water with rapid stirring and resulting solution was neutralized with ammonium hydroxide. A fiuify precipitate was obtained which was filtered off and dried at 90' parts of the N-methoxy methyl 60-65 Cr polyamide was obtained.

10 30 'parts of the above product was dissolved in parts of aqueous methanol by volume) containing 6.0 parts of thiourea at 5560 C. In

a reaction flask fitted with thermometer, stirrer i and condenser. After-approximately one hour of stirring the solution was cooled to30-35 C. and a solution of 7.66 parts of concentrated hydrochloric acid' (36% by'weight) in 12 parts of anhydrous methanol was added with continual stirring.

'The resulting solution which contained approximately 24% of polymer, based on the weight of the original 'N-methoxymethyl polyamide was diluted with 80% methanol to give a 4% solution of the polymer.

The shrinkproofing properties of the derivative was determined in the usual fashion and the following results wereobtained. The treated wool sample was cured at1'130 C. for 15 minutes.

Percent Poly- Relaxation Total Laundering Sample amide Shrinkage, Shrinkage, Shrinkage, on Percent Percent Percent sample Treated; 4. O G. 0 7 0.7 Untreated I v 0.0 9.9 44.0 34.1

Having thus set forth our invention, we claim: 1. The method of shrinkproofing 'wool with water-insoluble polyamides while retaining substantially normal hand which comprises impregnating the wool with an organic solvent solution of a water insoluble synthetic polyamide which contains hydrogen-bearing amide nitrogen atoms and having an intrinsic viscosity of at least 0.4. to deposit an amount not exceeding from about 1% to 25% by weight on the wool of polyamide insufiicient to modify the normal hand of the wool butsufiicient-ito give shrink-proofing and directly heating the impregnated wool in the absence. of precipitating agents for the polyamide thereby avoiding precipitation of the polyamide at a temperaturebelow that of substantial injury to wool or polyamide to insolubilize the polyamide and to give-a shinkp-roofed wool 0f normalhand, the organic solvent being a solvent whichdissolves and ismiscible with the polycarbonamide. I

2. The method of claim 1 in which the polyamide is a polyamide having in the main polyamide chain, recurring hydrogen bearing carbonamide groups separated by an average number of carbon atoms of at least 2. 3; The method of claim 1 in which the polyamide contains in the main polyamide chain recurring groups of the formula separated by an average number of carbon atoms amide contains in the main polyamide chain re curring groups of the formula -NOH2OR separatediby an average number of carbon atoms of at least 2, and where R. is selected from the group of alkyl and hydroxy alkyl radicals. I 6. The-method as set forthin claim 5 in which 11 the solution is. an aqueous alcoholisolutiorr ofra neutralized polyamide of the character. set: forth in claim 5.

7. The method asset forth in claim. inwhich the polyamide is. .the reaction. product ofan N- alkoxy methyl derivative ofa synthetic linear polyamide, with-zthiourea. I

8. The method as. set forth in claim 1* in which the heat treatment of the-impregnated wool'ineludes drying by heating at a temperature below 100 C. without, treatment with any precipitating agent for the polyamideand after drying, curing by heating at, a temperature above 100 C. but not exceeding a, temperature which injures the wool during the curing treatment'w-ithout-any treatment With a precipitating agent.

9,. The method asset forthin claim 1- in-which. the synthetic polyamide chain isselected from the group consistingof a polymethyleneamide of; a polymethylene dicarboxylic acid, a poly omegaamino acid and interpolymers of, the aforesaid specific polyamides.

10. A shrinkproofed wool of substantially normal hand carrying a heat only insolublized de posit from an organic solvent solution of a waterinsoluble synthetic polyamide which contains hydrogen-bearing amide nitrogen atoms and having an intrinsic viscosity of at least 0.4, in amount not exceeding from about 1% to 25% by weight on the wool insufficient to modify the normal hand of the wool substantially but suflicient to give shrinkproofing, the organic solvent being a solvent which dissolves and is miscible with the polycarbonamide.

11. Shrinkproofed woo1 as set forth in claim in which the polyamide is a polyamide havingin the main polyamide chain recurring hydrogen bearing carbonamide groups separated by an average number of carbon atoms, at least 2.

12. Shrinkproofed wool as set forth in claim 10 in which the polyamides contain in the main polyamide chain, recurring groups of the formula separated by an average numberof carbon atoms of at least 2.

13. Shrinkproofed wool asset forth in claim 12 in which the heat insolubilization is carried out below 100 C.

14; Shrinkproofed wool as set-forth in claim 10' in which the polyamide contains in the main polyamide chain, recurring groups of the formula separated by an average number of carbon atoms of at least 2, and where R. is selected from the group of alkyl and hydroxy alkyl radicals.

l5. Shrinkproofed wool as set forth in claim 14 in which the polyamide is the reaction product of an N-alkoxy methyl derivative of a synthetic linear polyamide as thiourea.

16. Shrinkproofed wool as set forth in claim 11 in which the deposit is a cured polymer.

17. Shrinkproofed wool as set forth in claim 11 in which the polyamide chain is selected from a group consisting of a polyethylene amide of a polymethylene dicarboxylic acid, a poly omegaamino acid and interpolymers of the aforesaid specific polyamides.

18. The method of claim 1 in which the amount of polyamide is from 2 to 7% by'weight on the wool.

19. The method of impregnating wool with 12- an organic solvent solution: of a water insoluble synthetic linear. polycarbonamide which contains hydrogen-bearingamide nitrogenatoms and having anintrinsic viscosity of at least 0.4, to deposit an amount of polyamide insufficient to modify the normal hand of the 'wool but suflicient to give shrinkproofing and'directly heating the impregnated wool in the absence of precipitating agents for the polyamide thereby avoiding precipitation boxylic acid in amount of. from 2 to 7% by weight on the wool, said method including drying'ata temperature offrom 60-100 C. and-curing at a temperature'of from C. to C.

20. The method of claim 19 in which'the polyamide contains'in the main polyamidechain recurring groups of the formula M caronseparatedby'an-average number of carbon atoms of at least 2.-

21. The method of claim 19 in which the polyamide containszi'n the main' polyamidechain recurring groupsof theformula separated .by an averagernumber of carbon atoms of at least 2, where R is selected from the group consisting ofalkyl. and hydroxy-alkyl radicals.

22. The-methodof; claim 1 innw-hich the poly.- arnide-is a poly w-amino acid inamount from 2% to 7% by Weight on the wool, said method to 150C.

23. The methodiof iclaim 22in which the'polyamide contains in the. mainv polyamide chain recurring groups of: the formula .NCHzOH separated by-an average number of carbon atoms of at least! 2.

24. Themethod of claim 22 in which the polyamide contains' in the main polyamide chain recurring groups of thezformula -C O 1' -CH2'0R separated-by an average numberof carbon atoms of at'least;2, where R' is' selected from-the group consisting of alkyl and hydroxyalkyl radicals.

25. The method" of claim 1 in which the polyamide is an interpolymer of a polymethylene amide of apolymethylene dicarboxylic acid and a poly w-amino acid,.in amount from 2 to 7% by weight on the wool said method including drying. at a temperature of. from 60100 C. and curing at a temperature of from 100 C. to 150 C.

26. The method'of claim 25in which the polyamide oontains in the main polyamide chain recurring groups of the formula 27. The method of claimizfiinwhich the-polyamide contains in the main polyamide chain recurring groups of the formula N-CH2OR separated by an average number of carbon atoms of at least 2, where R is selected from the group consisting of alkyl and hydroxyalkyl radicals.

28. Shrinkproofed wool produced by the method of claim 1 in which the polyamide is a polymethylene amide of a polymethylene dicarboxylic acid in amount of from 2 to 7 by weight on the wool.

29. Shrinkproofed wool as set forth in claim 28 in which the polyamide contains in the main polyamide chain recurring groups of the formula NCHzOH separated by an average number of carbon atoms of at least 2.

30. Shrinkproofed wool as set forth in claim 28 in which the polyamide contains in the main polyamide chain recurring groups of the formula NCH2OR separated by an average number of carbon atoms of at least 2, where R is selected from the group consisting of alkyl and hydroxyalkyl radicals.

31. Shrinkproofed wool produced by the meth- 1 od of claim 1 in which the polyamide is a poly w-amino acid in amount from 2 to 7% by weight on the wool.

32. Shrinkproofed wool as set forth in claim 31 in which the polyamide contains in the main polyamide chain recurring groups of the formula NCH1OH separated by an average number of carbon atoms of at least 2.

33. Shrinkproofed wool as set forth in claim 31 in which the polyamide contains in the main polyamide chain recurring groups of the formula 14 separated by an average number of carbon atoms of at least 2, where R is selected from the group consisting of alkyl and hydroxyalkyl radicals.

34. Shrinkproofed wool produced by the meth- 0d of claim 1 in which the polyamide is an interpolymer of a polymethylene amide of a polymethylene dicarboxylic acid and 'a poly w-amino acid in amount from 2% to 7% by weight on the wool.

35. Shrinkproofed wool as set forth in claim 34 in which the polyamide contains in the main polyamide chain recurring groups of the formula IRVING P. HAMMER. JOHN B. RUST.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,347,024 Beer Apr. 18, 1944 2,393,972 Cairns Feb. 5, 1946 2,406,958 McQueen Sept. 3, 1946 2,412,993 Larchar Dec. 24, 1946 2,430,859 Cairns Nov. 18, 1947 2,430,860 Cairns Nov. 18, 1947 2,443,450 Graham et a1. June 15, 1948 2,526,637 Cupery Oct. 24, 1950 

1. THE METHOD OF SHRINKPROOFING WOOL WITH WATER-INSOLUBLE POLYAMIDES WHILE RETAINING SUBSTANTIALLY NORMAL HAND WHICH COMPRISES IMPREGNATING THE WOOL WITH AN ORGANIC SOLVENT SOLUTION OF A WATER INSOLUBLE SYNTHETIC POLYAMIDE WHICH CONTAINS HYDROGEN-BEARING AMIDE NITROGEN ATOMS AND HAVING AN INTRINSIC VISCOSITY OF AT LEAST 0.4 TO DEPOSIT AN AMOUNT NOT EXCEEDING FROM ABOUT 1% TO 25% BY WEIGHT ON THE WOOL OF POLYAMIDE INSUFFICIENT TO MODIFY THE NORMAL HAND OF THE WOOL BUT SUFFICIENT TO GIVE SHRINK-PROOFING AND DIRECTLY HEATING THE IMPREGNATED WOOL IN THE ABSENCE OF PRECIPITATING AGENTS FOR THE POLYAMIDE THEREBY AVOIDING PRECIPITATION OF THE POLYAMIDE AT A TEMPERATURE BELOW THAT OF SUBSTANTIAL INJURY TO WOOL OR POLYAMIDE TO INSOLUBILIZE THE POLYAMIDE AND TO GIVE A SHINKPROOFED WOOL OF NORMAL HAND, THE ORGANIC SOLVENT BEING A SOLVENT WHICH DISSOLVES AND IS MISCIBLE WITH THE POLYCARBONAMIDE. 